This 5-year study, entitled "High-risk Establishments and Women's HIV Prevention in Southern China," is a Phase I/Phase II study of HIV risk and social dynamics in sex-work establishments, and the development and evaluation of a multi-level, site-based intervention conducted within those establishments to promote use of the female condom (FC) for HIV/STD prevention among women who work there. Based on a collaboration developed through an AIDS-FIRCA study, U.S. and Chinese investigators will work with Hainan and Guanxi provincial CDCs and local communities to conduct the study in two rural and two mid-sized urban towns in these provinces. The study aims are: 1) to assess the number and nature of sex-work establishments in these towns, and the stability and social dynamics within these establishments that affect delivery and testing of a site-base intervention to promote FC use for HIV prevention;2) to assess factors associated with HIV risk and use of female and male condoms for HIV prevention among women who work within these establishments;3) to develop, pilot, conduct a process evaluation, assess short-term efficacy and potential sustainability of, and manualize a site-based, multi-level (individual, site, community) intervention conducted in these establishments to promote the FC for HIV/STD prevention, and 4) to explore factors likely to explain: a) variation in feasibility, acceptability, and fidelity of intervention delivered in different establishments and different towns, and b) variation in short-term efficacy and sustainability of the intervention among women in different establishments and different towns. In each town we will use intensive ethnography to assess the characteristics and dynamics of sex workers and sex-work establishments, as well as the feasibility, process, and outcomes of the intervention conducted in those establishments. We will conduct cross-sectional surveys of sex workers in all 4 towns at three time points (baseline, 6 and 12 months post-baseline) for comparative analyses to assess town-level, sex-work establishment, and individual-level characteristics associated with HIV risk and prevention and outcomes of the intervention. Qualitative and quantitative data will be triangulated to build the strongest assessment of characteristics that affect risk and intervention outcomes and to provide the most comprehensive analysis of factors that enhance or impede use of the FC and other prevention measures by women in these establishments. Development and testing of the FC intervention has significant public health implications because of its potential for reducing sexual HIV transmission in this high-risk population and in the broader population of their sexual networks.